The invention relates to a drug for stimulating the rate of proliferation of liver cells, a liver protection and growth factor, and a method for producing them.
The extraction of a liver growth factor from the livers of partially hepatectomized rats is already known. Such a factor is a protein or proteide containing no amount of neuraminic acid of significance to the activity and having a molecular weight of between 30,000 and 50,000 D. The effect of this factor is organ-specific, but not species-specific. See Ruhenstroth-Bauer, Goldberg, Silz and Strecker, Hoppe-Seyler's Z. Physiol. Chem. 359, 543-545 (April, 1977); also see the earlier German patent application No. P 28 14 981.7-41 of Apr. 7, 1978 (corresponding to U.S. patent applications Ser. Nos. 973,666 and 028,304, both abandoned and 130,648, now allowed. As further prior art, see Demetriou, A. A. and Levenson, S. M., Annual Meeting of the American Association for the Study of Liver Disease, Nov. 6-8, 1978, Chicago, Ill., page 959. The subject of the earlier patent application is the extraction of a preliminary factor from the plasma of animals having partially hepatectomized livers, from which a liver growth factor can be split off by means of treatment with neuraminidase or neuramyltransferase. From this process of obtaining the liver growth factor, the following function model can be derived: The partially hepatectomized liver sends out a stimulus of some kind or other which, in a manner not yet known in detail, leads to the existence of the preliminary factor in the blood plasma. Then, by means, for example, of neuraminidase, which is present in increased amounts in the blood of partially hepatectomized animals, the preliminary factor is converted into the actual liver growth factor which causes proliferation of the liver cells.